Currently, you can get flair as HTML, Javascript, or JSON. Let's say I'm extra-cautious of XSS vulnerabilities. In that case the HTML and Javascript options are a no-no for me. JSON is possible if I use a trusted parser, but it's still just basically giving me HTML stored in a JS variable. A better option for me is a dynamically-generated image. You could cache the generated image for some time (say, 30 minutes?) to cut down on server demand.

Update: As pointed out by Kyle Cronin and rcar (see also meta.stackoverflow.com/questions/1238/…), a much greater need for this feature would be for use in sites which disallow iframes and scripting, for example when used as a sig on a forum, or when used on a blog hosted by wordpress.com.

Just to add to this, it would also allow the image to still work when SO is down for maintenance because the server serving the images could be entirely separate (and lightweight). I'd really like to see this too.

It would also reduce the need to have a time based image cache strategy.
–
Brad GilbertJul 1 '09 at 15:24

@brad: i think the time-based cache would still be a good idea... the code to generate an image (including fetching the gravatar image) is going to be several orders of magnitude slower than just reading a cached image. imagine if i include my flair image on a super popular site, then SO would have to generate the image millions of times at once. of course, maybe the overhead is low enough that this is still feasible... i'm just saying if i were designing it i'd use a time-based cache (and i was trying to head off potential excuses not to do this)
–
KipJul 1 '09 at 15:45

Image based flair shouldn't need to be cached less 64 hours. Seriously though, who needs his flair to be updated more than once a day or so? That would be very lightweight on the server.
–
perbertJul 12 '09 at 3:56

Expandable
Currently supports all 4 SO sites. Adapts to new additions to the StackOverflow family with a simple config file.

Examples

This script no longer works due to the new flair API. I have no intention of updating it.

The desktop theme included in the distribution will not render exactly the same as the above. The reason is that I didn't include one font used due to licensing restrictions. For reference, the reputation font (missing) is DIN 1451 Engschrift LT. The theme files are as in, so by dropping in the font as dinb.ttf in the system/fonts folder, it should render as the above.